docs: def split_param_vec(beta,
                      rows_to_alts=None,
                      design=None,
                      return_all_types=False,
                      *args, **kwargs):
      """
      Parameters
      ----------
      beta : 1D ndarray.
          All elements should by ints, floats, or longs. Should have 1 element
          for each utility coefficient being estimated (i.e. num_features).
      rows_to_alts : None,
          Not actually used. Included merely for consistency with other models.
      design : None.
          Not actually used. Included merely for consistency with other models.
      return_all_types : bool, optional.
          Determines whether or not a tuple of 4 elements will be returned (with
          one element for the nest, shape, intercept, and index parameters for
          this model). If False, a tuple of 3 elements will be returned, as
          described below.
  
      Returns
      -------
      tuple.
          `(None, None, beta)`. This function is merely for compatibility with
          the other choice model files.
  
      Note
      ----
      If `return_all_types == True` then the function will return a tuple of four
      objects. In order, these objects will either be None or the arrays
      representing the arrays corresponding to the nest, shape, intercept, and
      index parameters.
      """
      if return_all_types:
          return None, None, None, beta
      else:
          return None, None, beta